On Collective Computation

Postprint (published version

Unmanned Aerial Vehicles (UAVs) in environmental biology: A Review

Acquiring information about the environment is a key step during each study in the field of environmental biology at different levels, from an individual species to community and biome. However, obtaining information about the environment is frequently difficult because of, for example, the phenological timing, spatial distribution of a species or limited accessibility of a particular area for the field survey. Moreover, remote sensing technology, which enables the observation of the Earth’s surface and is currently very common in environmental research, has many limitations such as insufficient spatial, spectral and temporal resolution and a high cost of data acquisition. Since the 1990s, researchers have been exploring the potential of different types of unmanned aerial vehicles (UAVs) for monitoring Earth’s surface. The present study reviews recent scientific literature dealing with the use of UAV in environmental biology. Amongst numerous papers, short communications and conference abstracts, we selected 110 original studies of how UAVs can be used in environmental biology and which organisms can be studied in this manner. Most of these studies concerned the use of UAV to measure the vegetation parameters such as crown height, volume, number of individuals (14 studies) and quantification of the spatio-temporal dynamics of vegetation changes (12 studies). UAVs were also frequently applied to count birds and mammals, especially those living in the water. Generally, the analytical part of the present study was divided into following sections: (1) detecting, assessing and predicting threats on vegetation, (2) measuring the biophysical parameters of vegetation, (3) quantifying the dynamics of changes in plants and habitats and (4) population and behaviour studies of animals. At the end, we also synthesised all the information showing, amongst others, the advances in environmental biology because of UAV application. Considering that 33% of studies found and included in this review were published in 2017 and 2018, it is expected that the number and variety of applications of UAVs in environmental biology will increase in the future

Literature review and discussion on collaborative decision making approaches in industry 4.0

Nowadays, companies are faced with an increasingly higher level of competition while trying to adapt to the exigencies imposed by the Industry 4.0, regarding its usually referred dimensions and pillars, among which one that although is not so often referred is also expressing an increasing visibility and importance, related to collaboration, and more specifically to collaborative decision making and co-working. Thus, in this paper an analysis is carried out regarding the evolution of publications that have been put available over the last decade about collaborative decision making approaches, varying from approaches based on mathematical models up to the application of artificial intelligence and other kind of approaches. Moreover, a discussion about the relation between collaborative decision making, concurrent engineering and Industry 4.0 dimensions is also done.This work has been supported by FCT -Fundacao para a Ciencia e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020

Conceptual multi-agent system design for distributed scheduling systems

With the progressive increase in the complexity of dynamic environments, systems require an evolutionary configuration and optimization to meet the increased demand. In this sense, any change in the conditions of systems or products may require distributed scheduling and resource allocation of more elementary services. Centralized approaches might fall into bottleneck issues, becoming complex to adapt, especially in case of unexpected events. Thus, Multi-agent systems (MAS) can extract their automatic and autonomous behaviour to enhance the task effort distribution and support the scheduling decision-making. On the other hand, MAS is able to obtain quick solutions, through cooperation and smart control by agents, empowered by their coordination and interoperability. By leveraging an architecture that benefits of a collaboration with distributed artificial intelligence, it is proposed an approach based on a conceptual MAS design that allows distributed and intelligent management to promote technological innovation in basic concepts of society for more sustainable in everyday applications for domains with emerging needs, such as, manufacturing and healthcare scheduling systems.This work has been supported by FCT - Fundação para a Ciência e a Tecnologia within the R&D Units Projects Scope: UIDB/00319/2020 and UIDB/05757/2020. Filipe Alves is supported by FCT Doctorate Grant Reference SFRH/BD/143745/2019.info:eu-repo/semantics/publishedVersio

A glass half empty: Assessing the impact of empty flowers on foraging behaviour in three bee species

Flower-visiting insects face the difficult choice of selecting which flowers to visit and which to ignore. Foraging becomes more complicated because flowers can sometimes stop offering nectar, either due to removal by other visitors or because of physiological changes in the plant. In humans, items that are unexpectedly unavailable at the time of choice are called ‘phantom decoys’ and have been shown to influence preference relationships between other items in the choice set. If phantom decoys occur in pollinating insects, then the presence of empty flowers could have community-wide impacts on visitation rates of neighbouring flowers. In my first chapter, we tested if European honeybees Apis mellifera were susceptible to phantom decoy-style empty flowers. We then tested the effects of empty flowers on Bombus impatiens when they were influenced by the choices of their conspecifics. Finally, we tested if stingless bees, Tetragonula carbonaria made use of floral colour generalisations to choose flowers when the best flower in the choice set had its nectar removed. Overall, while we saw minimal impacts on floral choice by empty flowers, we did show that social behaviour is a key driver in allowing bees to make effective foraging decisions in the presence of empty flowers, and empty flowers can result in the abandonment of patches

Reading the news through its structure: new hybrid connectivity based approaches

In this thesis a solution for the problem of identifying the structure of news published by online newspapers is presented. This problem requires new approaches and algorithms that are capable of dealing with the massive number of online publications in existence (and that will grow in the future). The fact that news documents present a high degree of interconnection makes this an interesting and hard problem to solve. The identification of the structure of the news is accomplished both by descriptive methods that expose the dimensionality of the relations between different news, and by clustering the news into topic groups. To achieve this analysis this integrated whole was studied using different perspectives and approaches. In the identification of news clusters and structure, and after a preparatory data collection phase, where several online newspapers from different parts of the globe were collected, two newspapers were chosen in particular: the Portuguese daily newspaper Público and the British newspaper The Guardian. In the first case, it was shown how information theory (namely variation of information) combined with adaptive networks was able to identify topic clusters in the news published by the Portuguese online newspaper Público. In the second case, the structure of news published by the British newspaper The Guardian is revealed through the construction of time series of news clustered by a kmeans process. After this approach an unsupervised algorithm, that filters out irrelevant news published online by taking into consideration the connectivity of the news labels entered by the journalists, was developed. This novel hybrid technique is based on Qanalysis for the construction of the filtered network followed by a clustering technique to identify the topical clusters. Presently this work uses a modularity optimisation clustering technique but this step is general enough that other hybrid approaches can be used without losing generality. A novel second order swarm intelligence algorithm based on Ant Colony Systems was developed for the travelling salesman problem that is consistently better than the traditional benchmarks. This algorithm is used to construct Hamiltonian paths over the news published using the eccentricity of the different documents as a measure of distance. This approach allows for an easy navigation between published stories that is dependent on the connectivity of the underlying structure. The results presented in this work show the importance of taking topic detection in large corpora as a multitude of relations and connectivities that are not in a static state. They also influence the way of looking at multi-dimensional ensembles, by showing that the inclusion of the high dimension connectivities gives better results to solving a particular problem as was the case in the clustering problem of the news published online.Neste trabalho resolvemos o problema da identificação da estrutura das notícias publicadas em linha por jornais e agências noticiosas. Este problema requer novas abordagens e algoritmos que sejam capazes de lidar com o número crescente de publicações em linha (e que se espera continuam a crescer no futuro). Este facto, juntamente com o elevado grau de interconexão que as notícias apresentam tornam este problema num problema interessante e de difícil resolução. A identificação da estrutura do sistema de notícias foi conseguido quer através da utilização de métodos descritivos que expõem a dimensão das relações existentes entre as diferentes notícias, quer através de algoritmos de agrupamento das mesmas em tópicos. Para atingir este objetivo foi necessário proceder a ao estudo deste sistema complexo sob diferentes perspectivas e abordagens. Após uma fase preparatória do corpo de dados, onde foram recolhidos diversos jornais publicados online optou-se por dois jornais em particular: O Público e o The Guardian. A escolha de jornais em línguas diferentes deve-se à vontade de encontrar estratégias de análise que sejam independentes do conhecimento prévio que se tem sobre estes sistemas. Numa primeira análise é empregada uma abordagem baseada em redes adaptativas e teoria de informação (nomeadamente variação de informação) para identificar tópicos noticiosos que são publicados no jornal português Público. Numa segunda abordagem analisamos a estrutura das notícias publicadas pelo jornal Britânico The Guardian através da construção de séries temporais de notícias. Estas foram seguidamente agrupadas através de um processo de k-means. Para além disso desenvolveuse um algoritmo que permite filtrar de forma não supervisionada notícias irrelevantes que apresentam baixa conectividade às restantes notícias através da utilização de Q-analysis seguida de um processo de clustering. Presentemente este método utiliza otimização de modularidade, mas a técnica é suficientemente geral para que outras abordagens híbridas possam ser utilizadas sem perda de generalidade do método. Desenvolveu-se ainda um novo algoritmo baseado em sistemas de colónias de formigas para solução do problema do caixeiro viajante que consistentemente apresenta resultados melhores que os tradicionais bancos de testes. Este algoritmo foi aplicado na construção de caminhos Hamiltonianos das notícias publicadas utilizando a excentricidade obtida a partir da conectividade do sistema estudado como medida da distância entre notícias. Esta abordagem permitiu construir um sistema de navegação entre as notícias publicadas que é dependente da conectividade observada na estrutura de notícias encontrada. Os resultados apresentados neste trabalho mostram a importância de analisar sistemas complexos na sua multitude de relações e conectividades que não são estáticas e que influenciam a forma como tradicionalmente se olha para sistema multi-dimensionais. Mostra-se que a inclusão desta dimensões extra produzem melhores resultados na resolução do problema de identificar a estrutura subjacente a este problema da publicação de notícias em linha

Foraging Behaviour and Individuality in the Common Wasp (Vespula vulgaris)

The extreme ecological success of insect societies is frequently attributed to the division of labour within their colonies (Chittka & Muller, 2009; Holldobler & Wilson, 2009; E. Wilson & Hölldobler, 2005). Yet, we are far from understanding the causes and consequences of division of labour, implying workers’ specialization (Chittka & Muller, 2009; Dornhaus, 2008). Moreover, little studied is the behaviour of individual workers (Jeanson & Weidenmüller, 2013). Social wasps (Hymenoptera: Vespidae) have received less attention than social bees and ants, and our knowledge of basic aspect of their ecology is still poor (Jeanne, 1991; Greene, 1991). With my thesis, I aimed to contribute to a better understanding of the common wasp (Vespula vulgaris) foraging ecology and organization of labour. With a particular attention to their foraging behaviour, I investigated the inter-individual variability among wasp workers and their cooperation. My thesis shows evidence of information sharing and co-ordination in V. vulgaris foragers’ activity. In fact, the discovery and choice of resources by wasp foragers was assisted by information provided by experienced nestmates (Chapter 2). When resources known to portion of the workforce became newly available, the foraging effort of the whole colony increased. My observations of common wasps are hence consistent with foraging activation mechanisms and suggest piloting (in which one individual leads one or more nestmates to a resource) as a possible foraging recruitment mechanism in social wasps. I found huge variation in lifetime activity, task performance, and survival among common wasp workers (Chapter 3). Some individuals specialized on alternative foraging tasks over their lifetime, and a minority individuals performed a disproportionately high number of foraging trips (elitism). Foragers appeared to become more successful with age, accomplishing more trips and carrying heavier fluid loads. Compared to smaller nestmates, larger wasps contributed more to the colony foraging economies. High mortality was associated with the beginning of the foraging activity, relative to lower mortality in more experienced workers. I evaluated the performance of common wasp workers within the same insect colony, and found empirical support for the hypothesis that specialist foragers are more efficient than generalists (Chapter 4). In fact, V. vulgaris behavioural specialists performed more trips per foraging day and their trips tended to be shorter. Despite their more intense foraging effort, specialists lived longer than generalists. I investigated the intra-colonial variation in the sting extension response (SER) of common wasps, measured as a proxy for individual aggressiveness (Chapter 5). I found that wasps vary greatly in their SER and that individuals change during their life. Aggressive individuals tended to become more docile, while docile individuals more aggressive. Older wasps tended to be more aggressive. Wasp size was not significantly related to the SER. Wasp foragers had a less pronounced sting extension than individuals previously involved in nest defence. For the same individual, the aggressive response was proportional to the intensity of the negative stimulus

The Sub-Lethal and Density-Dependent Effects of an Invasive Wasp on an Endemic Ant

The detrimental effects of invasive species on recipient taxa are most frequently reported in terms of displacement or extinction. However, there may be other less obvious effects. For example, a reduction in resource availability mediated by a novel competitor may affect growth and development in recipient species. The cost of aggressive competitive interactions with invasives may promote niche shifts or altered spatial distribution to minimise competition, and intense predation by exotic species may result in a reduced effective population size with a concomitant reduction in genetic diversity. In this thesis I examined the sub-lethal effects of varying densities of the invasive competitor and predator Vespula vulgaris on the morphology, behaviour, population genetics and spatial distribution of the New Zealand endemic ant Prolasius advenus. The restriction of food resources can result in reduced worker size and altered scaling relationships of adult body parts in ants. Measurements of nine morphological characters from P. advenus worker ants collected from sites of varying wasp density revealed that workers were significantly smaller where there were more wasps. I also found evidence of allometric scaling relationships among body parts, which varied between areas of high and low wasp density. In particular the scaling relationships between the abdominal segments and overall size were found to be weaker where there were more wasps. This scaling variation resulted in ant workers with proportionally smaller abdomens in areas where wasps were most abundant, which might reduce their resource gathering and defensive efficiency. I tested the hypothesis that tasks performed by workers would be size correlated. In the presence of high densities of wasps, honeydew collection and brood care was undertaken by larger workers, whereas foraging in leaf litter was undertaken by smaller workers. In contrast, no relationship was found between task and worker size where wasp densities were lower. I suggest that in addition to increased efficiency in the collection of liquid carbohydrate resources larger workers may also serve a defensive role. I also tested the hypothesis that where the exclusively diurnal wasps were most abundant P. advenus workers would minimise potential competitive interactions by foraging predominantly at night. However, P. advenus were found to forage as much or more by day in the presence of high densities of wasps and to forage more nocturnally where wasps were sparse. Increasing the number of foragers by day may improve P. advenus’ competitive ability with wasps, but has the potential to come at the cost of other nest functions, energetic gains and increased worker mortality. Competitive mechanisms might influence ant population genetics, but wasps have also been shown to prey on dispersing ant queens. Analysis of microsatellite DNA markers revealed evidence of a genetic bottleneck in P. advenus populations where invasive predatory wasps have persisted at high population densities for more than twenty years. Ant populations at all wasp densities displayed significant heterozygote deficit, which may indicate that even at comparatively low densities predation by wasps has a detrimental effect on P. advenus genetic diversity. Alternatively, the observed heterozygote deficit may be the result of limited dispersal, population substructure or the peculiarities of the ant species‟ mating system. An examination of the broader population genetic structure of P. advenus from the seven sites sampled indicated that they were derived from two distinct populations. However, no individual assigned entirely to either population suggesting either some remaining admixture between the two populations or that they are derived from a common ancestral population. Finally I examined the effects of increasing wasp density, honeydew availability and habitat diversity on the distribution of P. advenus. Prolasius advenus nests tended to be smaller and populations displayed less variation in nest size where wasp densities were highest, which could indicate reduced longevity. Nest distribution was overdispersed relative to both con-and hetero-specific neighbours in high wasp density sites, but apparently randomly distributed in low wasp density sites. Both wasp and ant nest densities were greatest where honeydew was most abundant and plant diversity was lowest. These results suggest that intra- and inter-specific competition in combination with resource and nest site availability influences P. advenus nest distribution. Competition and predation by invasive species may influence recipient species‟ morphology, behaviour, genetic diversity and spatial distribution over a comparatively short period of time. These effects are much more subtle than under situations of direct predation. Such effects may not be immediately obvious in terms of abundance, but have potential long-term implications for the fitness and persistence of P. advenus in the presence of high densities of wasps

Behaviour of Foraging Bumble Bees Across Morphological and Environmental Contexts

Bumble bees as pollinators are being produced at an industrial scale and are used throughout the world to pollinate agricultural crops in glasshouses. The agricultural crops they are exposed to are often monocultural and mass-produced. The lack of floral variety they are provided with is thought to have negative effects on pollination performance and bee health, and has been suggested to influence worker drift in a glasshouse. Bumble bees are unique due to the large size differentiation among workers within a colony, which are thought to lead to consistent differences among individuals. Larger workers are more likely to be foragers, and smaller workers are more likely to perform in-nest tasks. These size differences are thought to cause differences among workers in foraging efficiency, the types of flowers they visit, and the size of their foraging ranges. Worker size also affects circadian rhythm strength, and individuals with stronger circadian rhythms are thought to anticipate potential activity cues such as sunrise. Bumble bees also show communication among foragers, but it is unknown whether they have ‘scouting’ bees that recruit inactive bees early in the day to forage. Understanding more about the behaviour of these populations and the effect environments can have on their activity is important for understanding how to aid in the conservation of these populations. Chapter 3 investigates bumble bee foragers and their activity among individuals of different sizes and within different colonies. I hypothesized (1) if bumble bees differ intrinsically from one another, then consistent differences in behaviour will be observed among foragers from the same colony and (2) if body size causes differences in anticipation of sunrise and foraging activity, then larger foragers will be seen initiating foraging earlier. To answer these questions, the nest entrance of two colonies were recorded that had access to a semi-natural floral environment in a glasshouse with tomato, cornflower and snapdragon flowers. Each bumble bee was marked with a coloured number tag to allow identification of each forager. Individuals differed from one another in foraging activity within both colonies. Additionally, larger workers initiated foraging earlier than smaller ones. The results support previous studies that show that individuals within a nest vary intrinsically from one another in foraging behaviour and show consistent differences within the same colony, as well as from other colonies. Moreover, larger bees appear to anticipate sunrise and potential food availability, suggesting the presence of strong diurnal foraging circadian rhythms, with larger bees leaving the next for the first time earlier than smaller bees. These differences among individuals could facilitate the temporal division of workers, and morphological differences could account for some of the variation seen among colonies. In chapter 4 I assessed bumble bee foraging activity across two different environments, a simple monofloral glasshouse, and an enriched polyfloral glasshouse. I hypothesised that (1) if simplified monocultures have a detrimental effect on bumble bee colonies, then decreased foraging activity will be observed in the simple environment compared to the enriched and (2) if nest switching behaviour is influenced by the availability of natural nectar sources, then lower levels of nest switching will be observed in the enriched environment. The methods of this chapter were the same as chapter 3, except that there were two glasshouses and four colonies. One glasshouse had 3 flower types including tomatoes, and the other only had tomatoes and artificial sugar syrup as a nectar source. I found that in the simple environment, bumble bees showed significantly decreased foraging activity, initiated foraging later, and spent less time out of the nest. Nest switching occurred at high rates and there was no difference among colonies or environments. These results show that bumble bee performance is affected by a monocultural glasshouse environment, and that nest switching occurs within a glasshouse independent of the environment they are exposed to. The research done in this thesis contributes to understanding bumble bee size differentiation and suggests that it may persist to separate workers temporally in activity. It shows differences among bumble bee foragers, and these foragers may differ from one another intrinsically or in thresholds to foraging tasks. It also provides insights into how monocultures and glasshouses can be affecting bumble bee colonies. This adds to literature about how monocultures may be having detrimental effects on pollinator species and reiterates the importance of providing a variety of floral resources to bees to enhance these populations